Black-backed gull

Braided River Status

Found on or over all non-forested habitats from coastal waters to high-country farms, it is abundant along all braided rivers.

Description

The Southern black-backed gull (Larus dominicans) karoro, (Maori), also known as the kelp gull, Dominican gull, mollyhawk, and seagull, is the largest gull and one of the most abundant large birds in New Zealand. It is also common in southern Australia, South America, southern Africa, most sub-antarctic Antarctic islands and the Antarctic Peninsula. Adults have white head and underparts with black back, yellow bill with red spot near tip of lower mandible, and pale yellow-greenish legs. Juveniles are dark mottled brown with black bill and legs; their plumage lightens with age until they moult into adult plumage at 3 years old. Juveniles may be confused with the stockier brown skua.

Black-backed gull and chicks – photo by Phillip Capper

Why is it a problem?

A scavenging bird, their population exploded as a direct result of human activities, primarily around garbage dumps, fish processing plants, and areas where effluent is discharged. While their populations have declined somewhat in the past few years as rubbish disposal has been improved, like all scavengers, they are opportunistic predators that readily kill river bird chicks – see the video below – and are increasingly implicated in the failure of entire breeding colonies of critically endangered endemicblack-billed gulls.

Conservation activities

The black-backed gull is one of only two native bird species not afforded any level of protection under the Wildlife Act. Black-backed gulls are often considered pests and on farmland, where some attack cast sheep and newborn lambs. As a result, they are sometimes shot, or controlled using toxins or by pricking their eggs. At a few sites, including the Waimakariri River and Hurunui River, they are controlled to reduce their predatory impacts on threatened birds.

A draft ‘issues and options’ report for controlling the population in areas where endangered and critically endangered braided river bird species was completed in late 2018 after public consultation. The final strategy is expected to be completed in 2019.

Important: in spite of their size, they are sometimes mistaken for the critically endangered black-billed gull or the declining red-billed gull. To avoid fines up to $300,000 for mistaken identity, any attempt to control black-backed gulls through shooting, trapping, poisoning, pricking eggs, or any other method, should only be undertaken after consulting with ECan or DOC in your area.